A new piezoelectric inertial rotary actuator by taking piezoelectric stacks as the power converters was proposed based on controlling the normal pressure to regulate the frictional force. By arranging two piezoelectric stacks symmetrically, the structure of the piezoelectric rotary actuator was designed, and its motion mechanism was explored. A prototype of piezoelectric rotary actuator was developed and the experimental test on the actuator was performed. Experimental results show that the actuator is excellent in linearity of output step and its rotation step is 20 μrad when the square wave is 10 V and the frequency is 2 Hz. The stability of the actuator was analyzed and an extra control system was added to overcome the shortcoming in the step stability at different start points. The error sources were obtained by analysis on the test data, which provides references for further optimization of the actuator. Research in this paper proves the feasibility of the design method for piezoelectric rotary actuators. It can be used in design of piezoelectric rotary actuators with simple structures, small volumes for micro-driving applications.